1. Field of the Invention
The present invention relates to a steering and suspension system for typical motorized snowmobiles in use for recreational purposes, and particularly to improving the maneuverability and safety of such snowmobiles.
2. Description of the Prior Art
The typical snowmobile used for recreational purposes today is not much different from the original recreational snowmobile developed by Armand Bombardier. The recreational snowmobile is propelled by a rear mounted cleated endless rubber track powered by a gasoline engine and steered by two forward mounted parallel skis. The driver turns the snowmobile by using a handlebar connected through a linkage to turn the skis in a parallel fashion with respect to the drive track. The uncertain footing provided by snow and ice make it difficult to control the typical snowmobile especially when travelling at speed. The ski suspension typical of early snowmobiles consisted of a downwardly arched leaf spring mounted on a typical ski such that the steering connected to and turned the leaf spring and consequently the ski, the leaf spring arching to provide cushioning to the ride and keeping the ski in contact with the snow. This type of suspension had very limited vertical travel and did not support the ski with much precision. Newer telescoping type ski suspension as described by West in U.S. Pat. No. 4,143,729 and Blanchard in U.S. Pat. No. 4,826,185 increased the usable vertical travel and provided integral damping means and better control of the ski. The most common type of ski suspension now in use is described by Talbot in U.S. Pat. No. 4,671,521. The trailing arm support with parallel transverse arms provides for excellent ski stability when turning and excellent vertical travel with a strong, relatively simple design. The transverse suspension arms are centrally mounted on the snowmobile and move the skis vertically in an arc instead of a straight line. This lateral ski displacement during compression of the ski suspension in conjunction with a relatively stable steering rod linkage causes the skis to toe out on compression of the suspension resulting in erratic steering or "bump steer". Current steering and suspension systems mount the ski axially about the vertical central turning point of the ski and support the snowmobile front end on the same point. The driver must shift his weight toward the inside of a turn to prevent the snowmobile from rolling over. This shift is necessary to bring the center of gravity of the driver --snowmobile combination closer to the inside turning arc to balance centrifugal cornering force with gravity to prevent rollover. Unpredictable footing on snow can often make this feat impossible and accidents occur, particularly for drivers not skilled in this type of maneuver. Prior snowmobile suspensions have been functional only in supporting the weight of the snowmobile by applying pressure to the skis and providing a laterally stationary bearing for ski rotation. Steering on prior snowmobiles has been by rotation of the ski about its center of support at the ski leg, providing the same level of lateral support on both sides of the snowmobile during cornering.
The skis on current snowmobiles generally have a keel on the bottom running surface which is approximately equal in length both forward and aft of the center of the ski in order to maintain ease of steering.
Snowmobiles by nature of their generally light weight and recreational use have very little in the way of safety features. Frontal collisions by snowmobiles almost always result in serious injury to the driver since there is no energy absorbing barrier between the driver and the object being struck.